In automation technology, process-oriented field devices are employed for acquiring and/or influencing process parameters. For this purpose, field devices are connected to sensors and/or actuators, or they are configured as sensors or actuators.
Currently, Ethernet is entering field level. For example the communication standard PROFINET enables communication of real-time critical data and other TCP/IP communication on one line at the same time. One application of TCP/IP communication is the configuration, monitoring and diagnosis of field devices using web technologies such as http or JavaScript. When PROFINET is employed, users may also use adjustment and diagnosis options via the already existing Ethernet interface of the device using a web browser.
Usually, a so-called PROFINET protocol stack is running in a PROFINET field device on a communications chip, such as e.g. an ERTEC chip from Siemens. This stack processes the PROFINET communication protocol independently. The stack provides its services at an application interface. These services allow a device application to read and write cyclic process data or acyclic parameter values.
Field devices are known which are provided with a web server for processing requests of an operation device provided with a web browser. By addressing the respective field device via an assigned URL address, visualization of information of the respective field device is possible in this way.
For implementing such a web access to a field device, the device manufacturer has to deal with details on web servers and web technologies concerning his device since the device application requires an interface to the web server. However, this is generally not a core competence of field device manufacturers. In addition, the web server requires additional computing power that will no longer be available for the device application.
When providing a web access, access conflicts may occur if for example a control unit such as a Programmable Logic Controller (PLC) and a web browser try to access a field device at the same time. These access conflicts have to be solved at the interface to the application. Furthermore, with the evolution from IPv4 to IPv6 the entire device architecture has to be adapted.